Identification of endothelial antigens relevant to transplant coronary artery disease from a human endothelial cell cDNA expression library.

Accelerated transplant coronary artery disease (TxCAD) results in increased expression of antiendothelial antibodies whose target antigens remain largely unidentified. One of these endothelial antigens has been identified as vimentin, a cytoskeletal protein present in cells of the blood vessel walls. In the present study, SDS-PAGE and Western blot analysis of human endothelial cell (EAHy 926) lysates probed with sera from a TxCAD patient were used to confirm immunoreactivity of antiendothelial antibodies towards several endothelial proteins. To further elucidate the identity of these putative antigens, a human endothelial cell (EAHy 926) cDNA expression library was immunoscreened with serum obtained from a TxCAD patient. Two positive cDNA clones were identified by partial nucleotide sequence analysis and GenBank/EMBL database searches for homology as the 85 kDa human CD36 antigen (a cell surface glycoprotein expressed in various cells including epithelial and endothelial cells) and a 50 kDa keratin-like protein (a member of the intermediate filament protein expressed in epithelial cells). These results are the first to demonstrate that human CD36 antigen and a keratin-like protein may be additional target proteins for the anti-endothelial antibodies associated with TxCAD.